When manufacturing an array substrate of a display device, a metal pattern such as a signal line, a source/a drain, or the like is usually made of a metal such as aluminum or copper, and layers such as a gate insulating layer, an etching stop layer, a passivation layer, or the like are formed on the metal pattern, and then dry etching is performed on the respective layers on the metal pattern at positions corresponding to the metal pattern using a gas such as oxygen to form connection holes for exposing the metal pattern so as to electrically connect the metal pattern from the outside. However, under the conditions of dry etching, the gas such as oxygen for drying etching may react with the metallic material of the metal pattern, resulting in occurrence of a bulge-like defect in the metal pattern. It has been found in the subsequent processes that the bulge-like defect may cause a series of problems such as pad erosion, failure in bonding, and the like. Unfortunately, the bulge-like defect is difficult to improve by changing the conditions of dry etching, which will seriously affect the quality of the final product and reduce the yield of the final product.
In view of the above, there is a need in the art for providing an improved array substrate of a display device.